REPRODUCTIVE ORGANS IN THE FEMALE. 323 



cells interlacing them, imparting strength and elas- 

 ticity to the uterine wall. There has been consid- 

 erable discussion as to the exact disposition of the 

 different layers of this musculature which, in a gen- 

 eral way, may be divided into three strata: (i) an 

 inner layer of longitudinal fibers, by some called 

 the muscularis mucosa; (2) a middle circular layer, 

 and (3) an outer thin layer of fibers that run diago- 

 nally or somewhat irregularly. The inner layer is 

 much the thickest; none, however, is sharply de- 

 fined. 



The serous coat is the peritoneal lining which con- 

 sists of connective- tissue elements and an invest- 

 ment of simple pavement epithelium. 



Vessels and Nerves. The arteries that supply the 

 uterus are arranged in two pairs, the uterine and 

 ovarian. The uterine artery is a branch of the an- 

 terior division of the internal iliac. It reaches the 

 upper portion of the vagina, and then ascends in a 

 very tortuous manner along the lateral border of the 

 uterus to the fundus, where it divides into two 

 branches, one of which anastomoses with the ovarian 

 artery and the other supplies the Fallopian tube. 

 From the ascending portion many side branches are 

 given off which penetrate the uterine wall and ramify 

 in the muscle tissue and the mucosa. These 

 branches are very tortuous so that the uterus 

 can expand in pregnancy without breaking the 

 vessels. 



The veins are very large and have no valves. 

 They form large sinuses mostly along the lateral 

 walls, from which the blood is collected into two 

 trunks: (i) the uterine vein accompanies the uter- 



